Semi-trailers have braking systems which are controlled through air system connections with the prime mover or tractor. The braking systems consist of service brakes, controlled from the brake pedal of the tractor, and emergency brakes which are operated either by air, actuated by a trailer brake lever in the tractor, or by spring loaded brake chambers which apply the brakes when air pressure is lost.
Each semi-trailer has two air lines, one each for service and emergency brakes, which must be connected to hoses on the tractor in order to receive a supply of compressed air. These air lines are terminated by rigidly mounted "glad hands" which are quick connectors at the front of the trailer and which receive the tractor air supply through rotatable "glad hands" at the ends of the tractor air hoses.
Whenever the trailer air system is unpressurized, the spring loaded brake chambers apply the brakes and thus prevent movement of the trailer. In order to release these spring actuated brakes, an air supply of sufficient pressure must be provided to override the spring force.
At truck freight terminals and marshalling yards there are many dozens of trailers awaiting handling and positioning. Relatively few can be handled at one time. The remainder are parked about the terminal until they can be handled by the loading crews. The movement of the trailers within the terminal or marshalling yard is generally accomplished by "yard jockeys" --small tractors which are dedicated to trailer movement, within the yard between the loading and parking areas.
Each time the "yard jockey" operator backs up to a trailer and engages the trailer king pin, he must exit the cab, connect the air hoses, re-enter the cab, and then release the trailer brakes before proceeding to move the trailer. This procedure is time consuming, inconvenient, and, during inclement weather, may be dangerous to the operator
The object of this invention is to provide a means whereby a "yard jockey" operator can engage the trailer king pin, establish his air connection, and release the trailer brakes quickly and easily without leaving the comfort and safety of his cab.